Ovarian cancer is a type of cancer that arises from the uncontrolled division and proliferation of cells in the ovaries, specifically in the epithelial cells that make up the main structure of the ovaries or in cells derived from the embryonic period. Eighty percent of ovarian cancers diagnosed after menopause originate in the epithelium. In ovarian cancers diagnosed in women under 20, embryonic tumors account for 60 percent of cases.